Enantioconvergent Cu-catalysed N-alkylation of aliphatic amines.

Chiral amines are commonly used in the pharmaceutical and agrochemical industries1. The strong demand for unnatural chiral amines has driven the development of catalytic asymmetric methods1,2. Although the N-alkylation of aliphatic amines with alkyl halides has been widely adopted for over 100 years, catalyst poisoning and unfettered reactivity have been preventing the development of a catalyst-controlled enantioselective version3-5. Here we report the use of chiral tridentate anionic ligands to enable the copper-catalysed chemoselective and enantioconvergent N-alkylation of aliphatic amines with α-carbonyl alkyl chlorides. This method can directly convert feedstock chemicals, including ammonia and pharmaceutically relevant amines, into unnatural chiral α-amino amides under mild and robust conditions. Excellent enantioselectivity and functional-group tolerance were observed. The power of the method is demonstrated in a number of complex settings, including late-stage functionalization and in the expedited synthesis of diverse amine drug molecules. The current method indicates that multidentate anionic ligands are a general solution for overcoming transition-metal-catalyst poisoning.

Copper-Catalyzed Enantioconvergent Radical N-Alkylation of Diverse (Hetero)aromatic Amines.

The 3d transition metal-catalyzed enantioconvergent radical cross-coupling provides a powerful tool for chiral molecule synthesis. In the classic mechanism, the bond formation relies on the interaction between nucleophile-sequestered metal complexes and radicals, limiting the nucleophile scope to sterically uncongested ones. The coupling of sterically congested nucleophiles poses a significant challenge due to difficulties in transmetalation, restricting the reaction generality. Here, we describe a probable outer-sphere nucleophilic attack mechanism that circumvents the challenging transmetalation associated with sterically congested nucleophiles. This strategy enables a general copper-catalyzed enantioconvergent radical N-alkylation of aromatic amines with secondary/tertiary alkyl halides and exhibits catalyst-controlled stereoselectivity. It accommodates diverse aromatic amines, especially bulky secondary and primary ones to deliver value-added chiral amines (>110 examples). It is expected to inspire the coupling of more nucleophiles, particularly challenging sterically congested ones, and accelerate reaction generality.

Copper-Catalyzed Enantioconvergent Radical C(sp3)-N Cross-Coupling of Activated Racemic Alkyl Halides with (Hetero)aromatic Amines under Ambient Conditions.

The enantioconvergent C(sp3)-N cross-coupling of racemic alkyl halides with (hetero)aromatic amines represents an ideal means to afford enantioenriched N-alkyl (hetero)aromatic amines yet has remained unexplored due to the catalyst poisoning specifically for strong-coordinating heteroaromatic amines. Here, we demonstrate a copper-catalyzed enantioconvergent radical C(sp3)-N cross-coupling of activated racemic alkyl halides with (hetero)aromatic amines under ambient conditions. The key to success is the judicious selection of appropriate multidentate anionic ligands through readily fine-tuning both electronic and steric properties for the formation of a stable and rigid chelating Cu complex. Thus, this kind of ligand could not only enhance the reducing capability of a copper catalyst to provide an enantioconvergent radical pathway but also avoid the coordination with other coordinating heteroatoms, thereby overcoming catalyst poisoning and/or chiral ligand displacement. This protocol covers a wide range of coupling partners (89 examples for activated racemic secondary/tertiary alkyl bromides/chlorides and (hetero)aromatic amines) with high functional group compatibility. When allied with follow-up transformations, it provides a highly flexible platform to access synthetically useful enantioenriched amine building blocks.

Emission Lifetimes of a Fluorescent Dye under Shock Compression.

The emission lifetimes of rhodamine 6G (R6G) were measured under shock compression to 9.1 GPa, with the dual intents of better understanding molecular photophysics in extreme environments and assessing the usefulness of fluorescence lifetime microscopy to measure spatially dependent pressure distributions in shocked microstructured media. R6G was studied as free dye dissolved in poly(methyl methacrylate) (PMMA), or dye encapsulated in silica microparticles suspended in PMMA. Thin layers of these materials in impedance-matched geometries were subjected to planar single-stage shocks created by laser-driven flyer plates. A synchronized femtosecond laser excited the dye at selected times relative to flyer plate arrival and the emission lifetimes were measured with a streak camera. Lifetimes decreased when shocks arrived. The lifetime decrease was attributed to a shock-induced enhancement of R6G nonradiative relaxation. At least part of the relaxation involved shock-enhanced intersystem crossing. For free dye in PMMA, the lifetime decrease during the shock was shown to be a linear function of shock pressure from 0 to 9 GPa, with a slope of -0.22 ns·GPa(-1). The linear relationship makes it simple to convert lifetimes into pressures. Lifetime measurements in shocked microenvironments may be better than emission intensity measurements, because lifetimes are sensitive to the surrounding environment, but insensitive to intensity variations associated with the motion and optical properties of a dynamically changing structure.

[Application of wavenumber-linear scaling to the calculated Raman frequencies of polyenes and carotenoids].

Raman spectra of two typical carotenoids (beta-carotene and lutein) and some short (n = 2-5) polyenes were calculated using density functional theory. The wavenumber-linear scaling (WLS) and other frequency scaling methods were used to calibrate the calculated frequencies. It was found that the most commonly used uniform scaling (UFS) method can only calibrate several individual frequencies perfectly, and the systematic result of this method is not very good. The fitting parameters obtained by the WLS method are upsilon(obs)/upsilon(calc)) = 0.999 9-0.000 027 4upsilon(calc) and upsilon(obs)/upsilon(calc)= 0.993 8-0.000 024 8upsilon(calc) for short polyenes and carotenoids, respectively. The calibration results of the WLS method are much better than the UFS method. This result suggests that the WLS method can be used for the frequency scaling of the molecules as large as carotenoids. The similar fitting parameters for short polyenes and carotenoids indicate that the fitting parameters obtained by WLS for short polyenes can be used for calibrating the calculated vibrational frequencies of carotenoids. This presents a new frequency scaling method for vibrational spectroscopic analysis of carotenoids.

Effects of Acute Interval Exercise on Arterial Stiffness and Cardiovascular Autonomic Regulatory Responses: A Narrative Review of Potential Impacts of Aging.

The physiological changes associated with aging deleteriously impact cardiovascular function and regulation and therefore increase the risk of developing cardiovascular disease. There is substantial evidence that changes in the autonomic nervous system and arterial stiffness play an important role in the development of cardiovascular disease during the aging process. Exercise is known to be effective in improving autonomic regulation and arterial vascular compliance, but differences in the type and intensity of exercise can have varying degrees of impact on vascular regulatory responses and autonomic function. There is still little evidence on whether there are differences in the response of exercise interventions to cardiovascular modulatory effects across the lifespan. In addition, acute interval exercise challenges can improve autonomic modulation, although the results of interval exercise on autonomic physiological parameters vary. Therefore, this narrative review focuses on evaluating the effects of acute interval exercise on blood pressure regulation and autonomic responses and also incorporates studies investigating different age groups to evaluate the effects of acute interval exercise on the autonomic nervous system. Herein we also summarize existing literature examining the acute cardiovascular responses to varied modes of interval exercise, as well as to further compare the benefits of interval exercise with other types of exercise on autonomic regulation and arterial stiffness. After reviewing the existing literature, it has been shown that with advancing age, changes in the autonomic nervous activity of interval exercise result in significant impacts on the cardiovascular system. We document that with advancing age, changes in the autonomic nerves lead to aging of the nervous system, thereby affecting the regulation of blood pressure. According to the limited literature, interval exercise is more effective in attenuating arterial stiffness than continuous exercise, but the difference in exercise benefits may depend on the training mode, intensity, duration of exercise, and the age of participants. Therefore, the benefits of interval exercise on autonomic and arterial stiffness improvement still warrant investigation, particularly the impact of age, in future research.

Measurement of infrared level lifetime by upconversion luminescence.

Based on repetition frequency-dependent excited state absorption (ESA) upconversion (UC) luminescence, a method to measure the lifetime of an IR intermediate level is proposed so long as ESA UC luminescence can occur in the rare earth ions. The feasibility of this idea is demonstrated via a theoretical simulation. A Er(3+):LiNbO3 crystal ESA UC luminescence under femtosecond laser excitation is used to illustrate this measurement method, and the obtained 1.5 µm lifetime of 2.31 ms is shorter than previous reported values. This method can obviate the influence of radiation trapping effect on lifetime measurement, which is crucial in the traditional pulse sampling technique.

Effect of end groups on the raman spectra of lycopene and ß-carotene under high pressure.

The Raman spectra of all-trans-lycopene in n-hexane were measured under high pressure, and the results compared with those of ß-carotene. The different pressure effects on Raman spectra are analyzed taking into account the different structures of lycopene and ß-carotene molecules. It is concluded that: (a) the vibronic coupling between the S1 and S0 states of ß-carotene is stronger than that of lycopene, (b) the diabatic frequency increment of the ν1 mode is more susceptible to pressure than that of the ν2 mode for lycopene, and (c) ß-rings rotation can relieve the pressure effect on the C=C bond length in ß-carotene. This work provides some insights for elucidating the structural and environmental effects on Raman spectra of carotenoids.

[Research on the spectral properties of the Rhodamine 101 dye].

The absorption, fluorescence and time-resolved fluorescence spectra of Rhodamine 101 dye in both methanol and acidic methanol solutions were measured. The authors achieved the characteristic information of the absorption and fluorescence spectra, and obtained the S1 lifetimes. The authors assigned vibrational modes of the Rhodanmine 101 dye molecule through spontaneous Raman spectrum, infrared spectrum, and density function theory calculation. This work systemically characterizes the spectral, molecular structural, and vibrational information of Rhodamine 101 dye molecule, and provides necessary information for the application of Rhodamine 101 dye in dye sensitized solar cell and biological fluorescence marker.

Lithium-induced overexpression of ß-catenin delays murine palatal shelf elevation by Cdc-42 mediated F-actin remodeling in mesenchymal cells.

BACKGROUND: Lithium chloride (LiCl) is widely used for the treatment of manic and other psychotic disorders, but the administration of lithium can result in several congenital defects in the fetus, including cleft palate (Meng, Wang, Torensma, Jw & Bian, 2015) (Szabo, 1970). However, the mechanism of Lithium's action as a developmental toxicant in palatogenesis is not well known. METHODS: In this study, hematoxylin-eosin and immunofluorescence staining were employed to evaluate the phenotypes and the expression of related markers in the LiCl-treated mice model. The palatal mesenchymal cells were cultured in vitro, and stimulated with LiCl or SKL2000, and co-treated with CASIN. ß-catenin protein and other cytoskeleton associated markers were evaluated by Western blotting. RESULTS: We found that Lithium disrupted palate elevation by increasing the expression of ß-catenin in C57BL/6J mice with the high incidence of cleft palate (62.5%). LiCl disturbed the F-actin responsible for cytoskeletal remodeling in mesenchymal cells, which proved to be essential in generating the elevating force during palatal elevation. Additionally, our Western blotting analysis revealed that the overexpression of ß-catenin resulted in up-regulation of Cdc42, which mediated the downstream F-actin synthesis. CONCLUSIONS: We concluded the LiCl-induced ß-catenin overexpression delayed murine palatal shelf elevation by disturbing Cdc42 mediated F-actin cytoskeleton synthesis in the palatal mesenchyme.

Structures and magnetic properties of electroless Ni multilayers on Fe/Si substrate.

Nanosized single and multiple layers of electroless Ni films were deposited on Fe film. The multilayer films consisting of a Fe/(Ni1 Ni2)n structure, where Ni1 and Ni2 denote various electroless Ni films deposited in plating baths with different pH values, and n denotes layer numbers and equals to 2, 4, 8, and 16, were formed by alternately changing the pH value of plating baths under controlled deposition time during the deposition process. The ensuing results showed that the boundaries between films are almost even. The deposition of various electroless Ni films on Fe film can increase the coercivity and squareness ratio of Fe film.

[The relationship between chest CT findings and viral load in patients with novel influenza A (H1N1)].

OBJECTIVE: To evaluate the value of chest CT findings and dynamic changes of viral load in patients with novel influenza A (H1N1) infection in clinical diagnosis, differential diagnosis and treatment. METHODS: Fifty-one patients with confirmed novel influenza A (H1N1) according to the diagnostic criteria of the Ministry of Health, received chest X-ray, CT scans (HRCT) and viral load tests in our hospital from May to December of 2009. Based on whether there were signs of pneumonia in CT imaging, the patients were divided into a pneumonia group (n = 31) and a non-pneumonia group (n = 20). The relationship between chest CT changes and viral load was observed and analyzed statistically using SPSS 10.5 software. RESULTS: Patchy consolidations of lungs were the main findings in pneumonia group with influenza A (H1N1) infection, and ground-glass opacities were the main CT findings at acute and convalescent phases. Lobular and segmental shadows of the lungs were diffusely distributed, mostly found in lower lungs, especially the left lung. In some cases, the lung diseases were accompanied with mediastinal lymphadenopathy. Co-existence of pulmonary parenchymal, interstitial and pleural diseases was observed. Peak viral load occurred at the early phase of illness, with the mean initial viral load being 7.7 copies/ml and 4.2 copies/ml in the pneumonia and the non-pneumonia groups respectively. The viral nucleic acid became negative 4 days after antiviral treatment (course of 6 days). Dynamic observation of 3 patients with novel influenza A (H1N1) pneumonia showed that, the viral clearance period preceded the absorption of lung lesions in 2 cases, but viral clearance period of a young patient was significantly prolonged. CONCLUSION: In patients with the novel influenza A (H1N1) infection, the viral load in the pneumonia group was significantly higher than that in the group with normal chest imaging. Dynamic observation on chest imaging and viral load may be beneficial for clinicians to start prompt and effective treatment.

Red upconversion emission in LiNbO3 codoped with Er3+ and Eu3+.

Red upconversion (UC) emission at 626 nm is obtained from a LiNbO(3) crystal codoped with Er(3+) and Eu(3+) under 800 nm femtosecond laser excitation. Energy transfer from ((2)H(11/2,),(4) S(3/2)) levels of Er(3+), which are excited by excited state absorption, to (5)D(1) of Eu(3+) followed by rapidly relaxing to (5)D(0) nonradiatively leads to this red UC emission. The energy transfer efficiency and Er-Eu transfer microparameter of approximately 30% is obtained in LiNbO(3):Er(3+)(1.0 mol%),Eu(3+)(0.1 mol%). These initial experimental results indicate that the red UC emission can be obtained from Er(3+)/Eu(3+) codoped system under diode laser excitation.

[Expression of Mycobacterium tuberculosis early secretory antigenic target-6 protein and its application in detection of Mycobacterium tuberculosis antigen-specific interferon-gamma response].

OBJECTIVE: To obtain the purified early secretory antigenic target-6 (ESAT-6) protein and to evaluate its application in detection of Mycobacterium tuberculosis antigen-specific interferon-gamma (IFN-gamma) response. METHODS: ESAT-6 protein was expressed by genetic engineering. The antigen specificity and reactivity of ESAT-6 were evaluated by Western blot. Using ESAT-6 as the antigen, the antigen-specific IFN-gamma response in patients with tuberculosis, healthy medical workers, and village residents was detected by the Elispot method. The results were also compared with those obtained by a commercial kit (QuantiFERON-TB-GOLD, QFT-G). RESULTS: ESAT-6 protein was successfully expressed and purified, and the antigen specificity of ESAT-6 was confirmed by its recognition by the antigen-specific antibody (anti-ESAT-6). The specificity and sensitivity of the Elispot assay using ESAT-6 as the antigen in detecting the IFN-gamma response was comparable with those of the commercial kit (QFT-G). The positive rates of the Elispot assay for patients with tuberculosis, healthy medical workers and villagers were 36/49 (73.5%), 11/62 (17.7%), and 17/194 (8.8%), respectively, while the rates of the OFT-G method for patients with tuberculosis and healthy medical workers were 38/49 (77.6%) and 14/58 (24.1%), respectively. The sensitivity (73.5%, 77.6%; chi2 = 0.381, P > 0.05) and specificity (82.3%, 75.9%; chi2 = 0.406, P > 0.05) of these two methods did not differ significantly. CONCLUSIONS: Recombinant ESAT-6 protein was expressed and purified. Elispot using recombinant ESAT-6 protein as antigen showed high sensitivity and specificity for detection of Mycobacterium tuberculosis antigen-specific IFN-gamma response. The purified ESAT-6 can be used for diagnosis of Mycobacterium tuberculosis infection.

LAPTM5 is transactivated by RUNX2 and involved in RANKL trafficking in osteoblastic cells.

The present study aimed to investigate the role of lysosomal­associated transmembrane protein 5 (LAPTM5) in osteoclast differentiation induced by osteoblasts. The results demonstrated that the expression levels of LAPTM5 were downregulated following runt­related transcription factor 2 (RUNX2) silencing and upregulated following RUNX2 overexpression in ST2 cells. Chromatin immunoprecipitation analysis identified the binding of RUNX2 to the LAPTM5 promoter at the ­1176 to ­1171 position. Dual­luciferase reporter assays confirmed that RUNX2 directly activated the LAPTM5 gene. The concentration of receptor activator of nuclear factor­κB ligand (RANKL) protein in the cytoplasm and in the media was significantly increased following LAPTM5 knockdown. LAPTM5 silencing in ST2 cells enhanced osteoclastic differentiation of co­cultured RAW264.7 cells. The present study indicated that expression of LAPTM5 was regulated by the interaction of RUNX2 with its promoter region and that LAPTM5 was involved in the trafficking of RANKL. These findings suggested a possible coupling mechanism between osteogenesis and osteoclastogenesis in which RUNX2 may be involved in osteoclast differentiation through the regulation of the lysosome­associated genes that modulate RANKL expression.

Effect of beta-ring rotation on the structures and vibrational spectra of beta-carotene: density functional theory analysis.

The effect of beta-ring rotation on the structures and vibrational spectroscopic characteristics of beta-carotene, including infrared (IR) intensities and Raman activities, is analyzed using density functional theory. Two stable isomers having Ci symmetry are obtained. The reversion of bond lengths is ascribed to the hyperconjugation effect. The natural bond orbital (NBO) charge analysis suggests that the NBO charges of C5 can be used to estimate the degree of pi-electron delocalization. These structural variations are used to analyze and assign the vibrational spectra. It is concluded that (a) the similar rotational angle dependencies of nu1 and nu2 frequencies justify the contribution of C=C stretch vibrations to the nu2 mode and explain the same conjugation length dependencies of nu1 and nu2 frequencies in polyenes, (b) the nu1 mode can be assigned to the C=C stretching in the central part of polyene chain, whereas beta-rings play an important role in nu2 and IR1 bands, especially for the all-trans isomer, and (c) the transition dipole moment of the calculated IR1 absorption band is relevant to the conjugation degree and the crossing angle between the eigenvectors of the polyene chain and the C5=C6 stretching vibration. This theoretical analysis, together with our previous Raman spectral experiments, suggests that the C6-C7 bond is easier to be twisted than other parts of beta-carotene molecule and so provides an insight into the structures of carotenoids and the properties of binding sites in carotenoproteins.

Relationship between respiratory viral load and lung lesion severity: a study in 24 cases of pandemic H1N1 2009 influenza A pneumonia.

OBJECTIVE: To investigate the relationship between respiratory viral load and lung lesion severity of patients with pandemic H1N1 2009 influenza A pneumonia. STUDY DESIGN: Cross-sectional observation study. METHODS: 24 consecutive H1N1 influenza patients with viral pneumonia (13 males, 11 females, mean age: 17.5 years) during their presentation to hospital were retrospectively analysed. Viral load were first measured on average 5.2 days after the onset of symptoms. The initial CT and viral load measurement was carried on the same day in 13 patients. The rest were carried out with a mean interval time of 1.5 days. All patients had viral load follow-up till turned negative. Thirteen patients had radiological follow-up. RESULTS: There was no significant correlation between the initial lung lesion severity and viral load (P=0.4). Both viral load and lung lesion severity decreased over time, being highest value at initial presentation. The patients had higher initial viral load or higher initial lung lesion severity tended to be slower in resolving. The lung lesion decreased at a slower rate than viral load. CONCLUSIONS: While there was no correlation between the initial viral load and lung lesion severity, these two indices provide valuable information for epidemiological control.

[The genetical evolution of the full length genes of 5 EV 71 strains from 5 Shenzhen patients with hand-food-mouth disease associated with EV71 infection].

OBJECTIVE: To investigate the characteristics of molecular epidemiology and molecular evolution of 5 EV 71 (enterovirus 71, EV71) strains from 5 Shenzhen patients with hand-food-mouth disease associated with EV 71 infection. METHODS: 5 EV 71 strains were isolated, and sequenced to analyzed the full length gene sequences in order to compare nucleotide and amino acid homology with other EV71 strains from other regions and countries as well as previous strains across the world through bioinformatics software. RESULTS: 5 strains of EV 71 belonged to sub-genotype C4 by analysis of nucleotide sequences of VP1 and VP4 of EV 71. The differences of nucleotide and amino acid sequences were much small with nucleotide homology of 93% and amino acid homology of 98% among these 5 strains. A phylogenetic tree analysis indicated that 2008 Shenzhen epidemic strains were the most close to 2004 Shenzhen circulating strains, and also much close to 1998 Shenzhen epidemic strains and 2008 Fuyang Anhui strains. The dead strain was very close to 2008 Fuyang Anhui epidemic strains. CONCLUSION: It can be speculated that this epidemic strains of EV 71 probably originate from the same ancient strain in the history, may from 1998 Shenzhen strain.

[Integration sites in HCC biopsy].

OBJECTIVE: To compare the performance of Inverse-PCR, Alu-PCR and Cassette-ligation-mediated PCR (CLM-PCR) in HBV DNA integration sites identification. METHODS: One HCC biopsy was obtained from surgically resected sample. The patient was positive for serum hepatitis B surface antigen (HBsAg). The genomic DNA was purified by the standard phenol/chloroform extraction and ethanol precipitation method. Seperated set of primers were designed to amplify the HBV DNA integration region by means of 3 different PCR methods respectively. The PCR products were analyzed by electrophoresis, then cloned to PMD18-T vector for DNA sequencing. The sequence alignment was performed under Blast software. RESULTS: 7 bands and 22 sequencing results was obtained from IPCR and 3 integration sites was identified. Alu-PCR provided 12 bands and 32 sequencing results, and CLM-PCR showed 12 bands and 4 sequencing results. No integration site was identified from the latter two. CONCLUSION: IPCR compared with another two methods showed a reliable capacity in HBV DNA integration site identification.

[Study on characteristics of cellular-mediated immune responses of novel H1N1 influenza A patients with pneumonia].

OBJECTIVE: To investigate the phenotype, frequency and function of CD4+ T cell subsets and the relevant cytokines, as well as the relationship between these cells and appearance of pneumonia of novel (H1N1) influenza A patients. METHODS: 68 healthy people, 53 confirmed novel A(H1N1) influenza patients without pneumonia and 16 confirmed severe novel A (H1N1) influenza patients with pneumonia were enrolled in this study. Viral load in nasopharyngeal swabs specimens was measured by real time PCR assay. The phenotype and percentage of CD4+ T cell subsets including Th1, Th2, Th17, and Treg cells were measured by Flow cytometry analysis. The relevant cytokines in plasma including TGF-beta, IL-6 and IFN-gamma were measured by ELISA. Data was analyzed by one way ANOVA. RESULTS: It was found that peak viral load and viral shedding period of severe patients with pneumonia was significantly increased compared with mild patients without pneumonia (P < 0.05). The percentage of Th17 cells of severe patients with pneumonia was significantly diminished compared to that of healthy subjects and mild patients without pneumonia (P < 0.05). However, Th1, Th2, Treg cells frequencies had no significant differences (P > 0.05) among these three groups. The level of TGF-beta in plasma for the severe patients with pneumonia was also significantly decreased compared to that of healthy subject and mild patients without pneumonia (P < 0.05). The viral shedding period inversely correlated with the frequency of Th17 cells (r = - 0.38, P < 0.05). CONCLUSION: H1N1 influenza A virus can inhibit Th17 cells to differentiate, particularly more extent in patients with pneumonia. Impaired Th17 cells may correlate with viral clearance and pneumonia of novel H1N1 influenza A patients.